The way i understand it, when one does a square a complete cycle of how many days they choose or is recommended, once you do the same one again it compounds with the the same exact type of previous square you have already done. Which makes the effects of them stronger the more you do them i think.
No, it will mess up the entire working. These numbers are specific and are in tune to the natural laws of the universe. Even doing another square of the same planet for another goal in mind will also mess up the square (Different planets are fine). Even doing one more or less repetition will ruin the square.